Differentiation between various types of particles is important in order to characterize the quality of a given formulation of drug product. For instance, low specificity in differentiation has the potential to confuse objects, such as glass lamellae, for proteinaceous particulate matter. High specificity of the differentiation system is needed in order to provide accurate decisions when making decisions on formulations. Without information about the type(s) of particles in a particular drug product, it may be difficult to formulate the drug product properly.
Unfortunately, conventional particle detection techniques are unsuitable for detecting protein aggregates and other small and/or delicate particles. Human inspectors usually cannot detect particles that are smaller than about 100 microns. Automated inspection techniques are typically destructive; that is, they involve removing the fluid being inspected from its container, which usually renders the fluid unsuitable for therapeutic use. In addition, conventional nondestructive inspection systems use only a single snapshot of the container to determine whether or not particles are present, which often leads to imprecise particle size measurements and/or particle counts. Conventional inspection techniques may also involve destruction of more delicate particles, such as protein aggregates. For example, spinning a vial filled fluid at high speed (e.g., 2000 rpm or more for several seconds) may rip apart protein aggregates in the fluid.